This invention relates to an apparatus for forming filler-provided beads for use in tires.
In most prior methods of forming a bead having a filler, the belt-shaped filler is supplied in a raised upstanding state to a bead rotating about its axis. A bottom side of the filler on its thicker edge is then urged against an outer circumference of the rotating bead so that the filler on the thicker edge is wrapped in a circle around the bead. Thereafter, longitudinal ends of the filler are butt joined with each other to form a filler-provided bead.
In this case, immediately after the filler 1 has been wrapped in a circle around the bead 2, a circle passing through an edge 3 of the filler 1 on a thin side is longer in circumferential length than a circle passing through an edge 4 of the filler 1 on a thick side. A V-shaped clearance 7 therefore occurs between the longitudinal ends 5 and 6 of the filler 1 as shown in FIG. 1. In order to butt joining the longitudinal ends 5 and 6 of the filler 1 under this condition, it is imperative to stretch the ends of the filler 1, increasing stretched lengths as approaching the thin edge 3 of the filler 1 on the thinner side thereof. As a result, the butt joining process can be realized only with difficulty such as uneven joining or insufficient joining strength
In order to avoid such a difficulty, it has been proposed that longitudinal ends of a filler 1 are cut as shown in phantom lines in FIG. 2 and cut surfaces are butt joined with each other. With the filler thus joined, however, a radial height h of the filler at the butt joined portion is higher than that of the remaining portion of the filler 1 as shown in FIG. 3. Such an unevenness in height of the filler adversely affects the uniformity of tires to be produced.